It is generally agreed that the best 19th century book on making daguerreotypes
is Samuel D. Humphrey's "American Handbook of the Daguerreotype." It is
available online at my "Digital Daguerreian Archive" WWW site at:
http://www.webcom.com/gwalker/digidag/
The traditional process uses a silver plate, polished to mirror smoothness, and
then sensitized with the vapors of iodine and bromine. It is then developed with
mercury vapor, fixed in thiosulphate, and toned with a fairly standard gold toner.
All of the vapors are toxic, though mercury has the worst reputation because it tends
to accumulate in the body and causes chronic poisoning.
However, it is possible to make good-looking daguerreotypes using only iodine
as a sensitizer and developing by long exposure to red light! This is called
Becquerel development. The technique is described in "Becquerel Development
in a New Light" by Gerald Megan, in the 1991 Annual of the Daguerreian Society.
Cheers,
Gregory Walker
Digital Daguerreian Archive -- http://www.webcom.com/gwalker/digidag/
"Electronic Texts from the Dawn of Photography"